@brief

According to the National Institute
of Mental Health, somewhere around 10
to 20 percent of Americans suffer from some form of a phobia. When the sufferer is exposed to the object they fear, problems can range from mild anxiety to full-fledged panic attacks. New
research from Hiroshima
University suggests that that our
irrational fears may be able to be turned off with the help of a common
anesthetic. The article that describes the results is published in the open access journal Behavioral and Brain Functions.

The experimenters trained commercially available
goldfish (Carassius
auratus)
to be afraid of light flashed in their eyes by having a flash of light followed by a low-voltage
electric shock. After a conditioning period, the researchers could
monitor the fish's heart rate and see it drop in response to the
stimuli—in a manner analogous to a human's heart rate rising during
a fear response—even in cases where there were no negative consequences.

The
researchers were able to show that, after an injection of a small amount of
lidocane
directly into the corpus cerebelli, the fish were unable
to learn
to be afraid. That is, once the lidocaine took effect, the conditioning
of the fish to associate the flash and electric shock no longer took. Future
flashes didn't slow the heart rate although, once the lidocaine wore off, the fish were still able to learn
to be scared of the conditioned trigger.

Now, any connection to humans may seem tenuous, but the vermal
part of a mammal's cerebellum has been suggested to be homologous to
the corpus cerebelli in fish. This may make the fish a useful model for studying ways of limiting the impact of phobias.